Fuel injection system



FUEL INJECTION SYSTEM 5 Sheets-Sheet l Filed June Jnson- 25' Cbm nu/er Camp/ex May 16, 1967 w. w. BEGLEY ETAL 3,319,613

FUEL INJECTION SYSTEM 3 Sheets-Sheet Filed June JMVEMraQS? Jgaaewr i; 7162.604,

)4 MAI/6521.

MPREM WflEGLE y 1967 w. w. BEGLEY ETAL FUEL INJECTION SYSTEM 3 Sheets-Sheet Filed June 5, 1965 4) T3 0 HMS E United States Patent Office 3,319,613 FUEL INJECTION SYSTEM Warren W. Begiey, Mission Hills, Robert E. Wilcox, North Hollywood, and Britten E. Kimball, Inglewood, Califi, assignors to Electronic Specialty Co., Los

Angeles, Calif., a corporation of California Filed June 3, 1965, Ser. No. 461,111

14 Claims. (Cl. 123--32) This invention relates to a fuel injection system for internal combustion engines and particularly to such a system of the continuous injection type in which fuel control is exercised by electrically operated means.

Fuel injection systems are known in which either liquid fuel is injected intermittently directly into the cylinders of an internal combustion engine, notably of the Diesel type, or in which intermittent injection occurs into an intake manifold or into a pre-ignition chamber. These fuel systems have often been extremely complicated, have employed high pressures and have often been of the allmechanical type.

We have found it possible to inject fuel of the gase line-kerosene type into the intake manifold in a continuous manner near the respective inlet ports of individual engine cylinders by low pressure means of a relatively simple system. We merely provide a positive displacement pump with an electro-magnetically controlled metering valve and bypass the excess fuel at low levels of en gine power back to the intake of this pump. The pressure in the metering cavity, which feeds plural fuel nozzles, is a direct function of the current energizing our electric metering valve.

Accordingly, electric control of the system is employed and various computer-like auxiliary controls are provided; such as for suiting the fueling requirements to ambient air temperature, altitude (ambient air pressure), engine speed and other parameters which need not be directly related to the operation of the engine proper.

This system is such that it can supplant the carburetor on an existing engine in an entirely practical modification of the fuel system. As such, it is applicable to automobiles, trucks, boats and airplanes and to numerous other engines of the spark ignition class. Such applications are not the only embodiments possible, but illustrate a typical field.

We employ speed-density metering rather than mass airflow metering in order to give reliable control at idle speeds and at low engine power output. Air external to the manifold of the engine is admitted through holes adjacent to the fuel spray in each fuel nozzle. This provides a portion of the air at idling.

More specifically, we provide an analog voltage to a fuel pressure control valve by means of an all solid state computer. This voltage represents the evaluation of necessary and desirable parameters for engine operation as represented in a given mathematical expression. A principal variable in the mathematical expression is engine speed. This is obtained by a tachometer which gives an electrical output. A cascade-connected pair of variable-inductance transformers in which the reluctance of the magnetic circuit is altered by ambient atmospheric pressure provides another term in the mathematical expression. Because of the pair of transformers the term is the square of the pressure variable. A further cascaded pair of such transformers operated by the manifold depression (degree of vacuum) provides another term proportional to the square of this pressure variable.

These variables are represented by amplitudes of pulsating voltage and the series connection of the electrical elements involved provides the product of these variables. An integrator element converts this product to a cor- Patented May 16, 1967 responding amplitude of non-pulsating voltage. A thermistor type temperature sensor is connected to the output of the integrator in a dual manner and provides a term proportional to the reciprocal of the square of the temperature of the air entering the manifold of the engine.

The electrical voltage analog of the whole mathematical expression thus synthesized is amplified to .power transistor output level and the output employed to provide current through the solenoid of an electro-controlled valve, such as the Electro-Magnetic Valve as described in the U. S. patent application, Ser. No. 38, 189, filed June 23, 1960 by Begley, Wilcox and Hoskinson. The fuel control exerted by this valve accomplishes desired engine performance according to the several variables sensed by the electrical computer.

An object of our invention is to provide an electronic computer-controlled fuel injection system.

Another object is to control a fuel injection system by suitably controlling an electric current through a bypass valve of that system.

Another object is to control a continuous injection fuel system by forming electrical energies proportional to desired powers of operational engine parameters and controlling the fuel delivered by said system in accordance with an electrically computed combination of said parameters.

Another object is to provide a relatively inexpensive fuel injection system constituted to perform in consonance with several parameters of engine operation.

Other objects will become apparent upon reading the following detailed specification and upon examining the accompanying drawings, in which are set forth by way of illustration and example certain embodiments of our invention.

In the drawing:

FIGURE 1 shows the mechanical and hydraulice aspects of our fuel system;

FIGURE 2 shows a block diagram of the electrical aspects of our system;

FIGURE 3 shows the schematic circuit diagram of the electronic computer of our invention; and

FIGURE 4 shows an electro-mechanical embodiment of our variable inductance transformers.

In FIGURE 1 numeral 1 indicates a liquid fuel reservoir or gasoline tank. From this, fuel is pumped through initial elements of the system, including a supply line 2, by known fuel pump 3, such as is found on automotive and similar engines of today. A check valve 4 is provided to prevent run-back of the fuel upon inoperation of the system. A filter 5 is provided next in line to hold back any foreign material in the fuel, since this would tend to clog the small orifices in the fuel nozzles. The filter may be of the known 10 micron degree of filtration capability.

Chamber 6 houses a positive displacement pump 7, a float 8 and a needle valve fuel shut-off 9. Elements 2 through 5 are normally completely filled with liquid fuel, but chamber 6 is partly filled with air due to the shut-01f action of the needle valve and float. This is provided so that the return of fuel to chamber 6 by the bypass action of subsequent elements can be accommodate. Float 8, acting through arm 10 and fulcrum 11, forces the needle of valve 9 tightly against a seat in inlet tube 12, thereby shutting off the flow of fuel into chamber 6 when this level reaches a predetermined height.

Pump 7 may be of the gear displacement type shown, having a casing 14 and two gears 15 and 16. One of the latter is connected to means to rotate the gears, such as a pulley engaging the fan belt of the engine (not shown). The inlet to the pump is at the bottom of casing 14 and the discharge is at the top and leads into discharge pipe 17. This pipe leads into the metering cavity 18 of the previously mentioned electro-magnetic fuel control valve 19. This valve has passage 20, throat 21, ball 22, solenoid 23 and bypass return pipe 24.

As disclosed in the specification for our Electro-magnetic Valve, the amount of fuel bypassed back through pipe 24 is such as to cause the fuel pressure in cavity 18 to be a linear function of the electric current through solenoid 23. The amplitude of this current is determined by the electrical control part of our system. This is represented in FIGURE 1 by the sensor-computer complex 25, which is connected electrically to the solenoid.

The correct fuel pressure for any given set of conditions is thus obtained. The fuel under this pressure is conveyed to nozzles located near the inlet valve for each cylinder in the internal combustion engine. In FIGURE 1, four such nozzles are shown: 26, 27, 28, 29. Hollow tubes or pipes 30, 31, 32, 33, connect between metering cavity 18 and one of the nozzles, respectively. Normally, we arrange the tubes symmetrically around the sides of the metering cavity. This cannot be so shown in FIGURE 1 because of the sectional showing of the cavity, but in practice tube 31 connects to the front of the cavity.

Each nozzle has a fuel orifice of the order of onehundredth of an inch in diameter and four bleeder air holes, as 34, of considerably larger size connected thereto at right angles. The air holes may be provided with mesh screen or similar filter material to prevent foreign bodies from entering the engine. Alternately, the air supply for these holes may be conveyed from the main air intake air filter through ducts which surround the group of four holes 34 on each nozzle.

In order to effect maximum fuel saving and also to prevent air pollution by the discharge of unburned hydrocarbons into the atmosphere through the engine exhaust We have provided an unloading valve 36. This is normally within chamber '6, but it may be located remotely therefrom and provided with a return tube to chamber 6 for returning temporarily unwanted fuel. Unloading valve 36 is solenoid operated and has a plunger 37 normally seated (closed) in discharge pipe 38 of pump 7 The closed position of the valve is maintained by compression spring 39. A paramagnetic core piece 40 is located within solenoid 41, which latter is connected to sensor-computer 25. As will be later detailed, when a relatively high vacuum occurs in the engine manifold a switch actuated by the sensor for this vacuum condition closes a circuit through solenoid 41. This causes core 40 to be pulled upward against the restoring force of spring 39 and plunger 37 is raised from seat 38. This allows the full discharge of pump 7 to be diverted back to chamber 6 rather than to flow through pipe 17 to the rest of the fuel system. It will be understood that the condition of high manifold vacuum is brought about by the reduction of air intake to the engine by a butterfly throttle valve, well known in this class of engine. In the terminology of the automobile, the operator has removed his foot from the accelerator.

We have found that our fuel injection system performs properly when the pressure 1P in the metering cavity 18 of the control valve is determined according to the following mathematical expression:

C'D(Nl-A)P"-'(0ZP-l-B) P where:

C =a constant. N =engine r.p.m.

A=a constant. dP=manifold depression (i.e. vacuum produced). B=a constant. P=atmospheric pressure. T=temperature of air entering mtnifold. D=acceleration step function. 7

Voltages proportional to the values of each of the above terms are developed by various means related to the operation of the engine. These voltages are combined to give a single analog type of computer control, as

will be outlined below and as is illustrated in FIGURE 2.

Equation 1 is derived as follows: The fuel flow through nozzles 26-29 is:

where:

Q =fuel fiow rate, lb. /hr. 7 C =nozzle coeflicient. P =nozzle pressure, lb./in.

From the characteristic of electromagnetic valve 19, see FIG. 4 of the copending application of Begley, Wilcox and Hoskinson, Electro-magnetic Valve, filed June 26, 1960, Ser. No. 38,189, and assigned to the. same assignee as this application, noting that the characteristic is linear:

'y=air-fuel ratio, lb. /lb. Q =air rate, la /hr. Q =fuel rate, lb. hr.

From the performance curves of modern engines, the mathematical expression for the amount of air inducted may be approximated by:

where From Equations 4 and 5 From Equation 2:

Then, from Equations 6 and 7:

J2 Y 25 P (N-l-A) (aP+B) T2 (8) By re-defining coefiicients and remembering that the cavity pressure P =nozzle pressure P (these volumes being connected by pipes 30-33) P CD(N+A)P (dP+B) 0 T2 which is identical to the Expression 1 previously given.

A tachometer electrical generator 45 is attached to a shaft of the engine, such as the positive displacement pump shaft. This generator produces a pulse having the approximate shape of a half-sinusoidal waveshape, one for each revolution. A magnetic piece of metal is attached to the shaft and a stationary coil is mounted adjacently thereto. 'The pulses are induced in the stationary coil. The repetition rate of the pulses is from ten to a few hundred cycles per second, depending, of course, upon the speed of rotation of the engine.

This provides the term N in fuel Equation (1).

An amplifier and clipper 46 is connected to the electrical output of tachometer 45 and serves to raise the voltage level and to provide a constant minimum voltage when the output from the tachometer is either small or is zero. This provides the term (N +A).

A one-shot multivibrator and amplifier 47 is connected to the output of the amplifier and clipper and provides a watt-second voltage in direct proportion to the term N. It removes the effect of electronic irregularities originating in any of the prior devices. A constant K is introduced by the inherent functioning of device 47.

The above voltage is then applied to two variablednductance transformers in series. The inductance of each is varied by movement of a small ferromagnetic core slug attached to atmospheric pressure-sensing diaphragm or bellows. The output of the first transformer 48 is K (N+A)P and out of the second transformer 49 is K (N+A)P The constant K and K are merely those originating with the electrical characteristics of the transformers.

This voltage is in turn applied to two more similar variable-inductance transformers 50 and 51, which are connected in cascade. The cores of these transformers are, however, translated with respect to the transformer coils by a diaphragm or bellows caused to distend inwardly of the manifold in accordance with the depression of the manifold pressure below atmospheric; i.e. proportional to the degree of vacuum created in the intake manifold. The voltage out of the first such transformer 56 is and out of the second transformer 51 is B is a constant. The constants K; and K are merely those originating with the electrical characteristics of these second transformers.

The last above voltage is then applied to an integrating circuit 52 with the capability to convert the voltage pulses to a uniform voltage level related thereto. The mathematical value of the output from the integrating circuit is the same as the above input, save that constant K becomes K This voltage is then applied to temperature sensor 53, the output of which varies as 1/1". This device contains thermisters; i.e., temperature sensitive resistors, in an otherwise temperature compensated circuit. The product of the 1/1 term and the prior terms results in the expression:

The basic mixture term C is obtained as an analog voltage from a potentiometer across a direct current electrical source. This is adjusted to obtain the term C/Kq. This is the mixture device 54 in FIG. 2.

An acceleration step voltage, D, is obtained from a switch 55 which is actuated by the manifold depression bellows. The switch is closed when this pressure dP falls to a predetermined small value; i.e., when the operator opens the air throttle wide to secure maximum power for accelerating the vehicle or the like. The switch gives an increased bias to output amplifier 57. This causes the amplifier to pass more current and thus to raise the pressure in the metering cavity 18 (of FIG. 1) and so to provide more fuel at the several nozzles.

Driver 56, in FIG. 2, is a medium power rated transistor employed to raise the energy level of the output from temperature sensor and mixture device 54 to a level suitable to drive the power transistor of output amplifier 57.

The output of output amplifier 57 is the full original mathematical expression, Equation 1, presented at the beginning of this discussion. This current is impressed upon solenoid 23 of fuel control valve 19, metering the pressure in cavity 18 in accordance with the expression stated. In FIG. 2 this parameter enters the fuel hydraulic system block 58.

It will be recalled that variable transformer 51 is con trolled by the reduction of pressure in the engine intake manifold. When the core element thereof is at the extreme position of maximum reduction of pressure a switch is actuated. This is connected to the solenoid 41 of unload valve 36 through a source of electrical energy and acts to shut off all fuel from the system, as has been previously mentioned.

We turn now to FIG. 3 in order to consider the electronic details of our analog computer and the sensors which coact with it.

Tachometer generator 45 is comprised of rotating magnet 60 and closely adjacent stationary coil 61. As has been mentioned, this device produces what might be termed the original signal for the computer, a pulsating voltage having an amplitude of a fraction of a volt and having a frequency depending upon the speed of rotation of the engine.

Capacitor 62 has been employed for practical reasons, to remove a spike of voltage of negative polarity from the electrical output of the tachometer at low engine speeds. The capacitor has a capacitance of the order of one-hundredth of a microfarad.

Transistor 63 acts as an amplifier. The base electrode 64 thereof is connected to the lower end of the tachometer coil and the emitter electrode 65 to the upper end of the coil, which is also a supply voltage connection through conductor 59 of, say, plus ten volts. An amplified output is obtained at the collector 66 of the transistor; the output having an amplitude of the order of 8 volts, peak to peak. This output occurs across resistor 67, which is connected to the collector 66 and to signal ground bus 68. The resistance of resistor 67 is of the order of thirty thousand ohms. Capacitor 69 has a capacitance of the order of a fraction of one microfarad and it conveys the signal to two silicon diodes 7t) and 71, which are connected in series to signal ground. Each of these diodes has a threshold of approximately one volt. This results in a two volt semi-square waveshape of the tachometer signal, limited in one polarity. Two more similar diodes 72, and 73 are connected in opposite olarity to that of the first two diodes. These limit the opposite excursions of the waveform and produce essentially a square waveform having a peak to peak amplitude of two volts.

This output is passed by capacitor 74, which capacitor has the same capacitance as capacitor 69, to a shunt-toground-connected resistor 75 having a resistance of the order of two hundred thousand ohms.

The limited waveform thus produced is conveyed directly to the base 76 of first transistor 77 of one-shot multibrator and amplifier entity 47. A second transistor 78 is connected back-to-back to form the multivibrator. All of the transistors thus far mentioned are of the usual low power germanium PNP type in present embodiments of our invention. The two emitters 79 and 80 of the two transistors are connected through a common resistor 81 to the plus ten volts supply. Resistor 81 has a resistance of a few hundred ohms. Collector 82 of first transistor 77 is connected to signal ground through resistor 83, which resistor has a resistance of the order of ten thousand ohms. Collector 82 is also connected through capacitor 84, of a tenth microfarad capacitance, to base 85 of transistor 78. Base 85 is also connected through resistor 86 of seven thousand ohms resistance to plus ten volts supply conductor 59. Collector 87 of transistor 78 is connected to the primary of a sub-miniature pulse transformer 89.

The limited Waveform input to the one-shot multivibrator insures that the duration of the output therefrom is uniform, when considered in relation to the time scale of the particular frequency generated by the tachometer at any time. This is the previously mentioned wattsecond voltage that is directly proportional to the tachometer output. This signal is amplified by medium power transistor 91, being introduced from secondary 90 to base 92. Emitter 93 is connected directly to plus ten volts conductor 59, while collector 94 connects to primary 95 of first variable inductance transformer 48, which senses the atmospheric pressure. The manner in which this occurs has been described and the structure itself is to be later described. Electrically, the output is induced in secondary 96, which is a typical embodiment has approximately the same number of turns as primary 95.

In cascade fashion, primary 97 of transformer 49 is connected directly to secondary '96 of prior transformer 48. The cores of both of these transformers are adjusted by the same mechanical means, thus a voltage proportional to the square of the atmospheric pressure is obtained at secondary 98 of transformer 49.

In exactly the same manner, transformers 50 and 51 are cascade-connected together, with primary 165 of transformer 50 connected to secondary 98 of transformer 49. In transformers '1? and 51 the I mechanical coreadjusting means is adjusted by a diaphragm sensing the decrease in pressure within the engine manifold and a voltage proportional to the square of this parameter is obtained. The parameter sensed by each transformer is multiplied by that of the other, thus giving the square.

In a typical embodiment, the voltage input to primary 95 of transformer 48 is of the order of ten volts. With the cores of all of the four transformers well within the respective coils, the voltage output is also ten volts. With the cores of all the transformers out of the coils, the opposite extreme condition, secondary 168 of transformer 51 is of the order of onetenth volt. It is to be understood that numerical values such as these may be much different in other embodirnents of our invention and still be wholly within that invention.

Integrator 52 takes the form of a full-wave bridge rectifier 100, having four diodes in this known configuration, and an output filter capacitor 101 with a capacitance of a few microfarads. Opposite terminals of this capacitor lead to opposite inputs of temperature sensor 53.

In temperature sensor 53, thermister type resistors 102 and 103 are located to measure the temperature of the air at the inlet to the engine manifold. These thermisters each have a resistance at 35 C. of the order of five hundred ohms. These have the known negative temperature characteristic of resistance typical of thermister 'material and reach the much higher value of resistance of the order of a hundred thousand ohms at 0 C. Each of the thermisters is shunted by a fixed resistor; 104 and 105, respectively each having a resistance of approximately fifteen hundred ohms.

The input to the temperature sensor from the lower terminal of capacitor 101 passes through resistors 106 and 107 in parallel, resulting in a combined resistance of the order of two thousand ohms, to the base 103 of transistor 109. The collector 110 of this transistor connects to thermister 102 and the shunting resistor 104 for the same. The opposite terminals of these resistive elements are connected to signal ground bus 68. The output of temperature sensor 53 is isolated from the direct current output of integrator 52 by diode 111 and an oppositely disposed companion diode 112.

The upper transistor 109 may be considered the basic temperature sensor transistor. The companion transistor 114 and its associated elements are for the purpose of maintaining the electrical characteristics of transistor 109 constant. regardless of ambient temperature variations impressed upon the computer as a piece of electrical apparatus. Transistor 109 and 114 are of the usual amplifying type, not of the power type.

Emitter 115 of transistor 109 is directly connected to collector 116 of transistor 114. The base 117 of the the voltage output from.

latter is connected to the base 103 of transistor 109 and also to one terminal each of resistor and thermister 103, the opposite ends thereof being connected to the upper terminal of integrator capacitor 101 and to isolation diode 112. Emitter 118 connects to another diode 119 and to a third thermister 120 in parallel. The op posite terminals of these two elements are connected to plus ten volt power supply bus 59.

The temperature sensor functions as follows. The voltage output of the integrator is impressed upon the base 103 of transistor 109. A corresponding output is obtained at collector 110, save that the load resistance of the latter circuit varies with temperature because of the temperature sensitivity of thermister 102. Suitably compensated, this is the output of the sensor and is impressed as a voltage upon base 121 of transistor 122 of driver entity 56. Thermister 103 decreases in resistance with temperature. This change results in a higher voltage at base 108 of transistor 109 and thus tends to cut off this transistor, giving less current through it. This effect, in combination with the reduction of resistance of thermister 102, give a U1 variation of voltage-at base 121 of the following driver transistor. We determined that the values of the inverse I/T function that are required to be evaluated in practice vary substantially linearly and that our circuit gave this evaluation. The voltage output to base 121 decreases, of course, with increase in temperature.

Compensation of the response of the transistor apparatus of our temperature sensor 53 with regard to ambient temperature takes place as follows.

Since transistors characteristically exhibit increased gain with increased temperature, transistor 114, thermister 120 and diode 119 in combination are series-connected with transistor 109 to compensate for the increased gain of transistor 114. Semiconductor diodes exhibit less forward resistance with increased temperature. The combination of the diode junction and the emitter diode junction of the transistor provide the correct emitter bias for transistor 109 regardless of temperature change by suitably changing the base potential at transistor 109 through the action of base current through transistor 114.

Thermister 120, in parallel with diode 119, does not affect circuit action until the higher ambient temperature ranges are reached, where it drops to the order of fifty ohms or less. This is necessary to match the characteristic of the diode junction to the characteristic of the transiStOr junction.

With increasing ambient temperature both transistors 109 and 114 tend to conduct more current. In particular,

the emitter voltage of transistor 114 becomes more positive. This also increases the emitter voltage of transistor 109 more positively. However, because of this situation, base current flows in transistor 114 and this raises the base potential of both transistors since these are connected together. The equilibrium existing at the lower ambient temperature is thereby maintained.

Driver transistor 122 is of the semi-power type. The emitter isconnected to the plus ten volts power supply bus 59 through resistor 123, which resistor has a resistance of the order of 1,000 ohms. Base 121 of this transistor is supplied with a direct voltage that varies according to all of the sensor-determined terms of mathematical Expression 1.

Collector 124 of the driver transistor connects directly to the variable resistance arm of potentiometer 125 in mixture entity 54. This potentiometer has a resistance of the order of 1,000 ohms and the extremities thereof connect across the full ten volts power supply, from negativematical Expression 1 is super-imposed over it due to the impedance between the variable arm and the signal ground at bus 68. In practice, the variable arm of potentiometer 125 is set once for a given engine and is seldom readjusted thereafter.

Also affecting the bias on base 126, but in an abrupt manner, is the series combination of a switch 128 and resistor 129 which is connected from the base to the negative ten volt bus 68 (signal ground). This combination comprises the accelerate step 55 of FIG. 2. When switch 128 is closed a more negative bias is placed on base 126 and power transistor 127 passes more current. Switch 128 is preferably a microswitch and is attached to the manifold-vacuum sensing assembly. Resistor 129 has a resistance of the order of one hundred ohms.

Emitter 128 of power transistor 127 is connected to the plus ten volt bus 59 through diode 129. This diode acts as a bias generator, since the voltage drop thereacross is approximately the same as the emitter diode junction of driver transistor 122. In this way the driver transistor is able to turn the output transistor 127 fully ion-,7

The collector 136 of power transistor 127 connects directly to solenoid 23 of fuel control valve 19. This direct connection gives electrical response down to zero frequency, which is necessary, of course, so that a constant amount of fuel can be injected into the engine for as long as desired.

In usual operation, a current variation of from ten milliamperes to one and one-half amperes is provided from the power transistor through this solenoid. The small current gives a low pressure in metering cavity 18 (see FIG. 1) because nearly all of the fuel passes beyond ball 22 and back to chamber 6. As the solenoid current increases, ball 22 is magnetically attracted to constrict the return passage. The pressure in cavity 18 then rises and the amount of fuel delivered to the nozzles in the intake manifold of the engine is increased.

Battery 132 is normally the twelve volt storage battery found on most internal combustion engine installations; being used for electric starting of the engine, lighting and other purposes. It is desirable that the voltage of the power supply for our computer be held constant. Ten volts is a suitable voltage magnitude. Accordingly, series fvoltage regulator entity 133 is provided.

A power type transistor 134 is connected in series with positive bus 59. The emitter 135 is connected to the positive terminal of battery 132 and collector 136 is connected to bus 59.

Ordinary transistors 137 and 138 accomplish the voltage control function by setting the bias between emitter 135 and base 139 of series transistor 134. Emitter 135 is connected to base 140 of transistor 137 through a resistor 141, having a resistance of the order of five thousand ohms. Emitter 142 is directly connected to base 139 of the series transistor.

A Zener diode 143 of the approximately five volt constant voltage drop characteristic is connected across the whole regulated voltage supply, from bus 59 to bus 68 through resistor 144 of some five hundred ohms, in order to provide a voltage reference. This voltage reference is impressed upon emitter 145 of transistor 138. Collector 146 thereof is directly connected to base 140 of transistor 137. Collector 147 of transistor 137 is directly connected to the plus ten volts bus 59, as one connection also for the Zener diode.

Base 148 of transistor 138 connects to potentiometer 149, at the variable arm. This gives a sample of the voltage existing between the regulated buses 59 and 68, the extremities of potentiometer 149 being connected to these conductors.

With this voltage impressed upon the base of transistor 138 and the emitter 145 being maintained at a constant potential because of the Zener diode connection thereto, it is seen that the output at collector 146 depends upon any departure of the regulated bus voltage from a predetermined value. This output is impressed upon base 140 of transistor 137, which in turn determines the emitter 1% -base 139 bias on series transistor 134. This bias is varied in the direction to remove the departure mentioned and so power supply output regulation is obtained regardless of conditions of operation tending to change the bus to bus voltage.

Details of the manifold variable reluctance transformer assembly are given in FIG. 4. Numeral indicates a sectional showing of the intake manifold of the engine. This is closed off by diaphragm 156, suitable for moving an appreciable fraction of an inch under the depression of manifold pressure below atmospheric to as low as a few inches of mercury; i.e., substantially a vacuum in the terminology of this art. The diaphragm is attached to the manifold by ring 157 and screws 158. An equivalent structure employing bellows as the pressure-actuated means for securing mechanical motion may be used as an alternate.

A non-magnetic rod forms the main part of the mechanically moving system. Conveniently, this rod is fabricated in three sections; 159, 160 and 161. Section 159 is suitably attached to the diaphragm in an air-tight manner, such as by bonding with epoxy cement. Iron slugs 162 and 163 alternate between rod sections 159-160 and 160- 161, respectively, and more similarly formed into a monolithic structure, as with epoxy cement. A compliant end support 164 gives mechanical stability to the moving system.

Variable inductance transformer 50 is located adjacent to iron slug 162, so as to provide variation of inductance thereof proportional to the pressure changes in the manifold encountered in engine operation. See FIG. 4. The primary coil is identified as 165 and the secondary as 166; both being shown in section. A similar relation exists between iron slug 163, primary 167 and secondary 168 of transformer 51. The variation of electrical inductance of these transformers previously recited is seen to be obtained as a function of the reduction of manifold pressure.

In addition, switch 128 is positioned to close electrical contact when diaphragm 156 relaxes to comparative flatness. A projection, 169, normally of insulating material, closes this switch by mechanical action. In practice we prefer to use enclosed switches of the microswitch type, but in FIG. 4 the switch details have been shown so that the functioning can be clearly interpreted. With the microswitch type, projection 169 need not be insulating and acts to depress the actuating plunger of the microswitch.

In a similar but reverse mode of operation, projection 170 actuates switch 171, to close the same when an external means causes an extreme magnitude of pressure reduction to occur in the manifold. Again, the microswitch type of a switch is suitable.

The point of rod travel at which each of these switches is actuated may be adjusted by moving the body of the same with respect to the stationary base 172 of the device, as is apparent.

As shown in FIGS. 2 and 3, as entities 55 and 128, respectively; switch 128 of FIG. 4 acts to increase the fuel for acceleration. This demand is impressed upon the engine by opening the throttle valve wide open and so the pressure within the manifold approaches atmospheric.

Conversely, switch 171 is adapted to close circuit when the reduction of pressure below atmospheric is extreme, as when decelerating. Contact at switch 171 in a series circuit with battery 132 (FIG. 3) closes unload valve 36 (FIGS. 1 and 2). This prevents appreciable amounts of fuel from passing into the engine and so increases fuel economy and decreases air pollution.

Variable inductance transformers 48 and 4-9 are similarly constructed, save that the connection to the manifold is not made, rather, to a hermetically sealed enclosure, and the switches are not required. The different air pressure encountered at different altitudes causes the operation of transformers 48 and 49.

It will be understood that modifications of the several elements and entities which comprise our fuel injection system may be made.

This may include further means for temperature compensation. Also, sensor means for responding to humidity may be provided, thereby to reduce the amount of fuel injected when the humidity is high. This is accomplished as an additional entity in the analog computer.

It is to be noted that a venturi in the manifold air flow is not required in our system. The system thus has excellent volumetric efiiciency and precise control of fuel flow under all conditions of engine operation.

Other modifications may be made in the arrangement, .size, proportions and shape of the various elements and entities of our system and in the electrical part thereof modifications in the characteristics of the circuit elements, details of circuit connections and alteration of the coactive relation between the elements may be made without departing from the scope of our invention.

Having thus fully described our invention and the man- Iner in which it is to be practiced, we claim:

1. A fuel injection system for a combustible fuel engine comprising a positive displacement pump, a continuous-fiow electrically-controlled valve, means to connect said valve as a bypass to said pump, plural continuous flow nozzles each connected to said valve, first means to form voltage pulses having a repetition rate proportional to the speed of revolution of said engine, second means connected to said first means to alter said voltage pulses according to a mathematical function proportional to atmospheric pressure, third means connected to said second means to also alter said voltage pulses according to a mathematical function proportional to the reduction of said atmospheric pressure within the fuel system of said engine, fourth means connected to the air input of said fuel system to form a voltage proportional to a mathematical function of the temperature of the air at said input, and electrical computer means connected to said third means and constituted to reform said altered voltage pulses to a corresponding direct electrical voltage, said computer means also connected to said fourth means to combine in an inverse manner said corresponding direct electrical voltage with said voltage proportional to a mathematical function of said temperature, and further means to connect said computer means to said electrically-controlled valve for the control of said engine.

2. A fuel injection system for an internal combustion engine comprising a positive displacement fuel pump, a continuous fiow electro-magnetic controlled metering valve having an inlet cavity, saidcavity connected to the discharge of said pump, the metered discharge of said valve connected as a bypass back to the intake of said pump, plural fuel lines connected to said inlet cavity, an engine inlet manifold, plural continuous flow fuel nozzles each having air inlet holes, each of said nozzles operatively attached to one of said fuel lines and positioned in said manifold adjacent to the inlet valve of each cylinder of said engine, means to produce voltage excursions at a repetition rate proportional to the speed of revolution of said engine, means to shape said excursions to uniformly shaped voltage pulses, means to modify the amplitude of said voltage pulses proportional to the square of the ambient atmospheric pressure, means to further modify the amplitude of said voltage pulses proportional .to the square of the reduction of said atmospheric pres- :sure Within said inlet manifold, means to rectify and integrate said further modified voltage pulses to a corresponding direct electrical voltage, said previously recited :means serially connected, means to form a direct electrical voltage output inversely proportional to the square -of the temperature of the air entering said manifold, and means to combine said corresponding direct electrical "voltage with that said electrical voltage inversely proportional .to the square of said temperature; and means to I2 impress the combined electrical voltage upon said electromagnetic controlled valve for the control of fuel to said engine.

3. In a fuel injection system for an engine having a fuel pump and an electrically-controlled fuel control valve connected to said pump, an electrical computer for the control of said fuel system comprising first means to form an alternating electrical output related to the speed of operation of said engine, second means connected to said first means to alter said electrical output in relation to the air pressure within said fuel system, third means connected to said second means to convert the altered said electrical output to direct current electrical energy, fourth means to form direct current electrical energy related to the temperature of air within said fuel system, fifth means connected to said third and fourth means to combine the electrical energies of the same, and means to connect said fifth means to said fuel control valve for the control of the latter in accordance with the recited electrically determined aspects of the operation of said engine.

4. In a fuel injection system for an engine having a fuel pump and an electrically-controlled metering valve connected to said pump, an electrical computer for the control of said fuel system comprising first means to form an alternating electrical voltage having a frequency related to the speed of revolution of said engine, second means connected to said first means to form electrical pulses of uniform energy content from said alternating voltage, third means connected to said second means to alter the energy content of said electrical pulses in relation to ambient atmospheric pressure, fourth means connected to said third means to further alter the energy content of said-electrical pulses in relation to the reduction of said atmospheric pressure within said engine, fifth means to rectify and filter connected to said fourth means to form a corresponding electrical voltage of one polarity, sixth means to form an electrical voltage related to the temperature of air entering said engine for burning said fuel, seventh means connected to said fifth and said sixth means to combine the electrical voltages of these means in reciprocal relation, and eighth means connected to said seventh means and to said metering valve for the control of the latter in accordance With the parameters of engine operation sensed by the several said means.

5. In the fuel injection system of claim 4, said first means comprised of a magnetic element, a coil, said magnetic element rotatable by said engine with respect to said coil to produce an electrical voltage in said coil, means to amplify said voltage, said means-to-amp lify connected to said coil, and bipolar diode means to limit excursions of said voltage, said diode means connected to said means to amplify.

6. In the fuel injection system of claim 4, said second means comprised of a one-shot mu-ltivibrator, a pulse transformer connected to said one-shot multivi-brator, and amplifying means connected to said pulse transformer.

'7; In the fuel injection system of claim 4, said third means comprised of plural cascade-connected varia'bleinductance transformers, each'having two coils, a movableferromagnetic core to variably couple said coils, and pressure-sensitive mechanical means exposed to the atmosphere and connected to saidcore to move the same.

8. In the fuel injection system of claim 4, said fourth means comprised of plural cascade-connected variableinductance transformers, each having two coils, a movable ferromagnetic core to variably couple said coils, and pressure-sensitive mechanical means exposed to air pressure within said engine, and connected to said core to move the same.

9. In the fuel injection system of claim 4, said fifth means comprised of a full-wave rectifier, a capacitor in shunt thereto, and two output terminals connected to said capacitor for connection to said seventh means.

10. In the fuel injection sysetem of claim 4, said sixth means comprised of a first transistor and a second transistor, a first negative temperature-coefficient resistor in one electrode circuit of said first transistor, a second negative temperature-coeflicient resistor in an electrode circuit of said second transistor dissimilar to said one electrode, a third negative temperature-coeflicient resistor in still another electrode of said second transistor dissimilar to said one electrode, and a semi-conductor diode connected across said third resistor; said first and second resistor disposed within said air entering said engine to measure the temperature of said air, and said second transistor, said third resistor and said diode coactive to maintain the electrical response of the circuitry of said sixth means independent of temperature.

11. In the fuel injection system of claim 4, said seventh means comprised of a first diode connected in one polarity between said fifth means and the first temperature-sensitive resistor of said sixth means, and a second diode connected in opposite polarity between two further temperature-sensitive resistors of said sixth means oppositely disposed therewithin with respect to said first resistor, and oppositely disposed conductors connecting said fifth means to said first and said second diodes.

12. In the fuel injection system of claim 4, said eighth means comprised of an amplifier connected to said seventh means, a potentiometer connected to said amplifier, a power amplifier connected to said amplifier and to said potentiometer, said potentiometer constituted and connected to set the bias upon said power amplifier to thereby set the reference amount of fuel delivered to said engine under the control of said computer, and means to connect said power amplifier to the coil of said metering valve.

13. In a fuel injection system for an engine having a fuel pump and an electrically-controlled continuous flow valve connected to said pump, an electrical computer for the control of said fuel system comprising first means to form alternating electrical energy having a frequency directly related to the speed of operation of said engine, second means connected to said first means to form uniform pulses of electrical energy from said alternating electrical energy, third means connected to said second means to alter the energy content of said electrical pulses as a second power function of atmospheric pressure of air, fourth means connected to said third means to further alter the energy content of said electrical pulses as a second power function of the reduction of air pressure within said engine, fifth means to electrically integrate connected to said fourth means to form an electrical voltage of one polarity corresponding to the energy content of the electrical pulses from said fourth means,'sixth means to form an electrical voltage as an inverse second .poler function of the temperature of air entering said engine for burning said fuel, seventh means connected to said fifth and said sisth means to combine the electrical outputs of the same, and eighth means connected to said seventh means and to said electrically-controlled valve for the control of the latter in accordance with the parameters sensed by the recited sensing means.

14. In a fuel injection system for a combustion engine having a fuel pump and an electrically-controlled continuous flow metering valve connected as a bypass to said pump, an electrical computer for the control of said fuel system comprising a tachometer generator to form an alternating electrical voltage having a frequency related to the speed of revolution of said engine, an electrical clipper and a driven relaxation oscillator connected to said generator to form electrical pulses of uniform energy content from said alternating voltage, plural cascaded variable-inductance transformers connected to said oscillator to alter the energy content of said electrical pulses in relation to ambient atmospheric pressure, further plural cascaded variable-inductance transformers connected to the prior said transformers to further alter the energy content of said electrical pulses in relation to the reduction of said atmospheric pressure within said engine, means to rectify and filter connected to said further transformers to form a corresponding electrical voltage of one polarity, temperature-sensitive resistive means to form an electrical voltage related to the temperature of air entering said engine for burning said fuel, further means connected to said filter and to said resistive means to combine the electrical voltage of the same in reciprocal relation, and means to connect said further means to said metering valve for the control of the latter in accordance with the parameters of engine operation sensed by the recited apparatus.

References Cited by the Examiner UNITED STATES PATENTS 2,606,420 8/1952 Moore 39.28 2,720,751 10/1955 Kunz 6039.28 2,843,096 7/1958 Dolza 1231 19 3,036,564 5/1962 Guiot 123l40.3 3,051,152 8/1962 Paule 12332 MARK NEWMAN, Primary Examiner.

R. D. BLAKESLEE, Assistant Examiner. 

3. IN A FUEL INJECTION SYSTEM FOR AN ENGINE HAVING A FUEL PUMP AND AN ELECTRICALLY-CONTROLLED FUEL CONTROL VALVE CONNECTED TO SAID PUMP, AN ELECTRICAL COMPUTER FOR THE CONTROL OF SAID FUEL SYSTEM COMPRISING FIRST MEANS TO FORM AN ALTERNATING ELECTRICAL OUTPUT RELATED TO THE SPEED OF OPERATION OF SAID ENGINE, SECOND MEANS CONNECTED TO SAID FIRST MEANS TO ALTER SAID ELECTRICAL OUTPUT IN RELATION TO THE AIR PRESSURE WITHIN SAID FUEL SYSTEM, THIRD MEANS CONNECTED TO SAID SECOND MEANS TO CONVERT THE ALTERED SAID ELECTRICAL OUTPUT TO DIRECT CURRENT ELECTRICAL ENERGY, FOURTH MEANS TO FORM DIRECT CURRENT ELECTRICAL ENERGY RE- 